1. Field of the Invention
The present invention relates to a technique for removably attaching multiple kinds of bit holders to a power tool in a manner of replacing with each other.
2. Description of the Related Art
Japanese laid-open patent publication No. 10-58352 discloses a technique for removably attaching multiple kinds of bit holders which hold tool bits in different manners and in a manner of being replaced with each other. The known bit holders each have an adapter which can be inserted into a spindle sleeve on the tool body side. When the adapter is inserted into the bore of the spindle sleeve, a locking member in the form of a ball which is held by the spindle sleeve and can move in the radial direction engages (locks) in a recess formed in the outer surface of the adapter. Thus engagement is maintained by a fixing member disposed on the outside of the adapter. Thus, the bit holder is attached to the slide sleeve and prevented from becoming detached from the slide sleeve. Further, the fixing member can move together with an operating sleeve for lock release which is axially movably disposed on the outside of the adapter. When the operating sleeve is moved away from the tool body (forward) against the biasing force of a compression coil spring, the fixing member releases the engagement of the ball with respect to the recess and allows the adapter to be pulled out of the spindle sleeve.
The known bit holder can be detached from the spindle sleeve when an operating force is applied to the operating sleeve in the direction of moving the operating sleeve away from the tool body. Therefore, during operation, when an external force is exerted by some chance on the opting sleeve in the direction of moving the operating sleeve away from the tool body, the bit holder may become detached from the spindle sleeve.